Use of dev_dbg() and friends is considered good practice.  dev_dbg() needs a
struct device *devp, but nsc_gpio is only a helper module, so it doesnt
have/need its own.  To provide devp to the user-modules (scx200 & pc8736x
_gpio), we add it to the vtable, and set it during init.

Also squeeze nsc_gpio_dump()'s format a little.

[  199.259879]  pc8736x_gpio.0: io09: 0x0044 TS OD PUE  EDGE LO DEBOUNCE
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Adds platform-device to (just introduced) driver, and uses it to replace many
printks with dev_dbg() etc.  This could trivially be merged into previous
patch, but this way matches better with the corresponding patch that does the
same change to scx200_gpio.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add the brand new pc8736x_gpio driver.  This is mostly based upon
scx200_gpio.c, but the platform_dev is treated separately, since its fairly
big too.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Since the meaning of config-bits is the same for scx200 and pc8736x _gpios, we
can share a function to deliver this to user.  Since it is called via the
vtable, its also completely replaceable.  For now, we keep using printk...
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now that the read(), write() file-ops are dispatching gpio-ops via the vtable,
they are generic, and can be moved 'verbatim' to the nsc_gpio common-support
module.  After the move, various symbols are renamed to update 'scx200_' to
'nsc_', and headers are adjusted accordingly.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add the nsc_gpio common-support module as an empty shell.  Next patch starts
the migration of the common gpio support routines.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now actually call the gpio operations thru the vtable.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Abstract the gpio operations into a new nsc_gpio_ops vtable.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

[PATCH] chardev: GPIO for SCx200 & PC-8736x: refactor scx200_probe to better segregate _gpio initialization

Pull shadow-reg initialization into separate function now, rather than doing
it 2x later (scx200, pc8736x).  When we revisit 2nd drvr below, it will be to
reimplement an init function, rather than another refactor.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add a new driver command: 'v' which calls gpio_dump() on the pin.  The output
goes to the log, like all other INFO messages in the original driver.  Giving
the user control over the feedback they 'need' is construed to be a
user-friendly feature, and allows us (later) to dial down many INFO messages
to DEBUG log-level.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Shrink scx200_gpio_dump() to a single printk with ternary ops.  The function
is still ifdef'd out, this is corrected in next patch, when it is actually
used.

The patch 'inadvertently' changed loglevel from DEBUG to INFO.  This is Good,
because in next patch, its wired to a 'command' which the user can invoke when
they want.  When they do so, its because they want INFO to support their
developement effort, and we want to give it to them without compiling a DEBUG
version of the driver.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Per kernel headers, device minor numbers are unsigned ints.  Do the same in
this driver.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add a platform-device to scx200_gpio, and use its struct device dev member
(ie: devp) in dev_dbg() once.

There are 2 alternatives here (Im soliciting guidance/commentary):

- use isa_device, if/when its added to the kernel.

- alter scx200.c to EXPORT_GPL its private devp so that both scx200_gpio,
  and the (to be added) nsc_gpio module can use it.  Since the available devp
  is in 'grandparent', this seems like too much 'action at a distance'.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Adopt many modern 2.6 coding practices, ala LDD3, chapter 3.  Changes are
limited to initialization calls from module init, ie: cdev_init, cdev_add,
*_chrdev_region, mkdev.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

GPIO SUPPORT FOR SCx200 & PC8736x

The patch-set reworks the 2.4 vintage scx200_gpio driver for modern 2.6, and
refactors GPIO support to reuse it in a new driver for the GPIO on PC-8736x
chips.  Its handy for the Soekris.com net-4801, which has both chips.

These patches have been seen recently on Kernel-Mentors, and then
Kernel-Newbies ML, where Jesper Juhl kindly reviewed it.  His feedback has
been incorporated.  Thanks Jesper !

Its also gone to soekris-tech@soekris.com for possible testing by linux folks,
I've gotten 1 promise so far.  Theyre mostly BSD folk over there, but we'll
see..

Device-file & Sysfs

The driver preserves the existing device-file interface, including the
write/cmd set, but adds v to 'view' the pin-settings & configs by inducing,
via gpio_dump(), a dev_info() call.  Its a fairly crappy way to get status,
but it sticks to the syslog approach, conservatively.

Allowing users to voluntarily trigger logging is good, it gives them a
familiar way to confirm their app's control & use of the pins, and I've thus
reduced the pin-mode-updates from dev_info to dev_dbg.

I've recently bolted on a proto sysfs interface for both new drivers.  Im not
including those patches here; they (the patch + doc-pre-patch) are still quite
raw (and unreviewed on KNML), and since they 'invent' a convention for GPIO, a
proper vetting is needed.  Since this patchset is much bigger than my previous
ones, Id like to keep things simpler, and address it 1st, before bolting on
more stuff.

The driver-split

The Geode CPU and the PC-87366 Super-IO chip have GPIO units which share a
common pin-architecture (same pin features, with same bits controlling), but
with different addressing mechanics and port organizations.

The vintage driver expresses the pin capabilities with pin-mode commands
[OoPpTt],etc that change the pin configurations, and since the 2 chips share
pin-arch, we can reuse the read(), write() commands, once the implementation
is suitably adjusted.

The patchset adds a vtable: struct nsc_gpio_ops, to abstract the existing gpio
operations, then adjusts fileops.write() code to invoke operations via that
vtable.  Driver specific open()s set private_data to the vtable so its
available for use by write().

The vtable gets the gpio_dump() too, since its user-friendly, and (could be
construed as) part of the current device-file interface.  To support use of
dev_dbg() in write() & _dump(), the vtable gets a dev ptr too, set by both
scx200 & pc8736x _gpio drivers.

heres how the pins are presented in syslog:

[ 1890.176223]  scx200_gpio.0: io00: 0x0044 TS OD PUE  EDGE LO DEBOUNCE
[ 1890.287223]  scx200_gpio.0: io01: 0x0003 OE PP PUD  EDGE LO

nsc_gpio.c: new file is new home of several file-ops methods, which are
modified to get their vtable from filp->private_data, and use it where needed.

scx200_gpio.c: keeps some of its existing gpio routines, but now wires them up
via the vtable (they're invoked by nsc_gpio.c:nsc_gpio_write() thru this
vtable).  A driver-spcific open() initializes filp->private_data with the
vtable.

Once the split is clean, and the scx200_gpio driver is working, we copy and
modify the function and variable names, and rework the access-method bodies
for the different addressing scheme.

Heres a working overview of the patchset:

# series file for GPIO

# Spring Cleaning
gpio-scx/patch.preclean        # scripts/Lindent fixes, editor-ctrl comments

# API Modernization

gpio-scx/patch.api26        # what I learned from LDD3
gpio-scx/patch.platform-dev-2    # get pdev, support for dev_dbg()
gpio-scx/patch.unsigned-minor    # fix to match std practice

# Debuggability

gpio-scx/patch.dump-diet    # shrink gpio_dump()
gpio-scx/patch.viewpins        # add new 'command' to call dump()
gpio-scx/patch.init-refactor    # pull shadow-register init to sub

# Access-Abstraction (add vtable)

gpio-scx/patch.access-vtable    # introduce nsg_gpio_ops vtable, w dump
gpio-scx/patch.vtable-calls    # add & use the vtable in scx200_gpio
gpio-scx/patch.nscgpio-shell    # add empty driver for common-fops

# move code under abstraction
gpio-scx/patch.migrate-fops    # move file-ops methods from scx200_gpio
gpio-scx/patch.common-dump    # mv scx200.c:scx200_gpio_dump() to nsc_gpio.c
gpio-scx/patch.add-pc8736x-gpio    # add new driver, like old, w chip adapt
# gpio-scx/patch.add-DEBUG    # enable all dev_dbg()s

# Cleanups

# finish printk -> dev_dbg() etc
gpio-scx/patch.pdev-pc8736x    # new drvr needs pdev too,
gpio-scx/patch.devdbg-nscgpio    # add device to 'vtable', use in dev_dbg()

# gpio-scx/patch.pin-config-view    # another 'c' 'command'
# gpio-scx/quiet-getset        # take out excess dbg stuff (pretty quiet
now)
gpio-scx/patch.shadow-current    # imitate scx200_gpio's shadow regs in
pc87*

# post KMentors-post patches ..

gpio-scx/patch.mutexes        # use mutexes for config-locks
gpio-scx/patch.viewpins-values    # extend dump to obsolete separate 'c' cmd

gpio-scx/patch.kconfig        # add stuff for kbuild

# TBC
# combine api26 with pdev, which is just one step.
# merge c&v commands to single do-all-fn
# delay viewpins, dump-diet should also un-ifdef it too.

diff.sys-gpio-rollup-1

This patch:

Removed editor format-control comments, and used scripts/Lindent to clean up
whitespace, then deleted the bogus chunks :-(
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make use the of newly defined hotplug version of cpu_notifier functionality
wherever appropriate.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Define new macros register_hotcpu_notifier() and unregister_hotcpu_notifier()
that redefines register_cpu_notifier() and unregister_cpu_notifier() for use
only when HOTPLUG_CPU is defined.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make notifier_calls associated with cpu_notifier as __cpuinit.

__cpuinit makes sure that the function is init time only unless
CONFIG_HOTPLUG_CPU is defined.

[akpm@osdl.org: section fix]
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make notifier_blocks associated with cpu_notifier as __cpuinitdata.

__cpuinitdata makes sure that the data is init time only unless
CONFIG_HOTPLUG_CPU is defined.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

CPUs come online only at init time (unless CONFIG_HOTPLUG_CPU is defined).
So, cpu_notifier functionality need to be available only at init time.

This patch makes register_cpu_notifier() available only at init time, unless
CONFIG_HOTPLUG_CPU is defined.

This patch exports register_cpu_notifier() and unregister_cpu_notifier() only
if CONFIG_HOTPLUG_CPU is defined.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch reverts notifier_block changes made in 2.6.17
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In 2.6.17, there was a problem with cpu_notifiers and XFS.  I provided a
band-aid solution to solve that problem.  In the process, i undid all the
changes you both were making to ensure that these notifiers were available
only at init time (unless CONFIG_HOTPLUG_CPU is defined).

We deferred the real fix to 2.6.18.  Here is a set of patches that fixes the
XFS problem cleanly and makes the cpu notifiers available only at init time
(unless CONFIG_HOTPLUG_CPU is defined).

If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run
time.

This patch reverts the notifier_call changes made in 2.6.17
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We need to serialize access to the global rtc_idr even in this error path.
Signed-off-by: NSonny Rao <sonny@burdell.org>
Acked-by: NAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There are two locking sets involved.  One locks the board mappings and the
other is the tty open/close locking.  The low level code was clearly
designed to be ported to OS's with spin locks already so pretty much comes
out in the wash
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Corey Minyard <minyard@acm.org>

The kthread used to speed up polling for IPMI was using udelay in its
busy-wait polling loop when the lower-level state machine told it to do a
short delay.  This just used CPU and didn't help scheduling, thus causing
bad problems with other tasks.  Call schedule() instead.
Signed-off-by: NCorey Minyard <minyard@acm.org>
Acked-by: NMatt Domsch <Matt_Domsch@dell.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add operations for the call_rcu_bh() variant of RCU.  Also add an
rcu_batches_completed_bh() function, which is needed by rcutorture.
Signed-off-by: NPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add an ops vector to rcutorture, and add the ops for Classic RCU.  Update
the rcutorture documentation to reflect slight change to the dmesg formats.
Signed-off-by: NPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This just catches the RCU torture documentation up with the recent fixes
that test RCU for architectures that turn of the scheduling-clock interrupt
for idle CPUs and the addition of a SUCCESS/FAILURE indication, fixing up
an obsolete comment as well.
Signed-off-by: NPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix kernel-doc parameters in kernel/

Warning(/var/linsrc/linux-2617-g9//kernel/auditsc.c:1376): No description found for parameter 'u_abs_timeout'
Warning(/var/linsrc/linux-2617-g9//kernel/auditsc.c:1420): No description found for parameter 'u_msg_prio'
Warning(/var/linsrc/linux-2617-g9//kernel/auditsc.c:1420): No description found for parameter 'u_abs_timeout'
Warning(/var/linsrc/linux-2617-g9//kernel/acct.c:526): No description found for parameter 'pacct'
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix TCSBRK comment to prevent confusion or accidental removal.
Signed-off-by: NPaul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add missed ufsi->i_dir_start_lookup initialization in ufs_read_inode in
UFS2 case.  Also it cleans ufs_read_inode function to prevent such kind of
situation in the future: it move depend on UFS type parts of code into
separate functions and leaves in ufs_read_inode only generic code.  It
cleans code and avoids duplication.
Signed-off-by: NEvgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

generic_file_buffered_write() prefaults in user pages in order to avoid
deadlock on copying from the same page as write goes to.

However, it looks like there is a problem when write is vectored:
fault_in_pages_readable brings in current segment or its part (maxlen).
OTOH, filemap_copy_from_user_iovec is called to copy number of bytes
(bytes) which may exceed current segment, so filemap_copy_from_user_iovec
switches to the next segment which is not brought in yet.  Pagefault is
generated.  That causes the deadlock if pagefault is for the same page
write goes to: page being written is locked and not uptodate, pagefault
will deadlock trying to lock locked page.

[akpm@osdl.org: somewhat rewritten]
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We include config.h on the compiler command line. There's no need for it
to be included again.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

locking init cleanups:

 - convert " = SPIN_LOCK_UNLOCKED" to spin_lock_init() or DEFINE_SPINLOCK()
 - convert rwlocks in a similar manner

this patch was generated automatically.

Motivation:

 - cleanliness
 - lockdep needs control of lock initialization, which the open-coded
   variants do not give
 - it's also useful for -rt and for lock debugging in general
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

- add a proper prototype for the following global function:
  - buffer_init()

- make the following needlessly global function static:
  - end_buffer_async_write()
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add more poison values to include/linux/poison.h.  It's not clear to me
whether some others should be added or not, so I haven't added any of
these:

./include/linux/libata.h:#define ATA_TAG_POISON		0xfafbfcfdU
./arch/ppc/8260_io/fcc_enet.c:1918:	memset((char *)(&(immap->im_dprambase[(mem_addr+64)])), 0x88, 32);
./drivers/usb/mon/mon_text.c:429:	memset(mem, 0xe5, sizeof(struct mon_event_text));
./drivers/char/ftape/lowlevel/ftape-ctl.c:738:		memset(ft_buffer[i]->address, 0xAA, FT_BUFF_SIZE);
./drivers/block/sx8.c:/* 0xf is just arbitrary, non-zero noise; this is sorta like poisoning */
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Update two drivers to use poison.h.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Localize poison values into one header file for better documentation and
easier/quicker debugging and so that the same values won't be used for
multiple purposes.

Use these constants in core arch., mm, driver, and fs code.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Acked-by: NMatt Mackall <mpm@selenic.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Move the i386 VDSO down into a vma and thus randomize it.

Besides the security implications, this feature also helps debuggers, which
can COW a vma-backed VDSO just like a normal DSO and can thus do
single-stepping and other debugging features.

It's good for hypervisors (Xen, VMWare) too, which typically live in the same
high-mapped address space as the VDSO, hence whenever the VDSO is used, they
get lots of guest pagefaults and have to fix such guest accesses up - which
slows things down instead of speeding things up (the primary purpose of the
VDSO).

There's a new CONFIG_COMPAT_VDSO (default=y) option, which provides support
for older glibcs that still rely on a prelinked high-mapped VDSO.  Newer
distributions (using glibc 2.3.3 or later) can turn this option off.  Turning
it off is also recommended for security reasons: attackers cannot use the
predictable high-mapped VDSO page as syscall trampoline anymore.

There is a new vdso=[0|1] boot option as well, and a runtime
/proc/sys/vm/vdso_enabled sysctl switch, that allows the VDSO to be turned
on/off.

(This version of the VDSO-randomization patch also has working ELF
coredumping, the previous patch crashed in the coredumping code.)

This code is a combined work of the exec-shield VDSO randomization
code and Gerd Hoffmann's hypervisor-centric VDSO patch. Rusty Russell
started this patch and i completed it.

[akpm@osdl.org: cleanups]
[akpm@osdl.org: compile fix]
[akpm@osdl.org: compile fix 2]
[akpm@osdl.org: compile fix 3]
[akpm@osdl.org: revernt MAXMEM change]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@infradead.org>
Cc: Gerd Hoffmann <kraxel@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>